Recently, the calibration of three-dimensional vibration sensor is usually based on a single dimension vibration calibration system, which calibrates the three axes of the sensor one after another. Inevitably, this method consumes too much time and complicates the data processing system. In the meantime, considering the cross-axis coupling of the three-dimensional sensor, it is hard to obtain the sensitivity matrix, which represents the coupling relations between the three axes of the sensor based on this method. So development of a three-dimensional standard vibrator, which output vibration exciting signals to the three axes of the three-dimensional sensor, has important theoretical and practical significance on the development of vibration sensor calibration technology and the progressing of related industry technology.
Chinese patent CN 201110207297.5 announces a three-dimensional standard vibrator based on a latch-type decoupling device. The vibrator consists of a base, three single-dimensional electromagnetic vibrators along X, Y, and Z axis, and a three-dimensional vibration platform. Each of the single-dimensional vibrators is connected with the three-dimensional vibration platform through a motion decoupling device. The motion decoupling device consists of the first and second frameworks, which are intersected with each other. The two frameworks all comprise the outer frame, the inner frame, the first and second lateral frames between the outer and inner frames. The outer frame is opposite to the inner frame, and the inner frame from one of the frameworks is inserted into another framework. The inner frame of the first framework is drilled with gas channels and vent holes, and the two ends of the vent holes are connected with the gas channels and the outside atmospheres. The second framework is installed with the inner frame and outer frame both have little intervals to the inner frame of the first framework, and the intervals could form aerostatic guide rails. There is an interval between the inner frame of the second framework and the outer frame of the first framework to avoid interfering of the two frameworks. The gas channels are connected with the outside pressured gas sources. The two outer frames of the first framework and the second framework are connected with the electromagnetic vibrator and the three-dimensional vibration platform, respectively. The latch-type structures and the aerostatic guide rails are utilized in the vibrator to realize force transmissions and to solve the issue of motion decoupling for three-dimensional vibrations.
The shortcomings of the proposed vibrator are as follow. The required accuracy of the assembling is excessively high since the first and second frameworks are mounted on the vibrator and the three-dimensional vibration platform respectively, and the two frameworks are inserted with each other with latch-type structure. Besides, the second framework increases the mass of the three-dimensional vibration platform and the stiffness of the gas film is relatively a restriction when used for vibration transmissions in high frequencies.